Pollution monitoring, and fire protection and suppressant systems may operate by detecting the presence of smoke and other airborne pollutants. Upon a threshold level of particles being detected, an alarm or other signal may be activated and operation of a fire suppressant system and/or manual intervention may be initiated.
As illustrated in FIG. 1A, air sampling pollution monitoring equipment in the form of aspirated particle detection systems (1) may incorporate a sampling pipe network (2) consisting of one or more sampling pipes (3, 4, 5, 6) with one or more sampling holes, or inlets (3A, 4A, 5A, 6A), installed at positions where smoke or pre-fire emissions may be collected from a region or environment being monitored, which is ordinarily external to the sampling pipe network. Air is drawn in through the sampling holes and subsequently along the pipe or pipe network (2) by means of an aspirator or fan (7) and is directed through a detector (8) at a remote location. Sampling points in the form of the sampling inlets are located at regions where particle detection is required. These regions are typically distant from the actual detector. Although there are a number of different types of particle detectors which may be used as the detector in a system as outlined above, one particularly suitable form of detector for use in such a system is an optical scatter detector, which is able to provide suitable sensitivity at reasonable cost. An example of such a device is a VESDA® LaserPlus™ smoke detector as sold by the applicant. Multi-tube aspirated gas or smoke alarm systems such as that illustrated in FIG. 1A enable early detection of a smoke and/or gas event, and also the ability to quickly locate the source of such an event.
One such system is shown in GB 2243475B which describes a rotary air selector valve that enables rapid detection of an event followed by rapid location of the source and also gives the ability to capture transient events and to distinguish between transient and continuing events. Such a valve 9, as indicated, is used in the system of FIG. 1A to connect the multiple sampling pipes 3, 4, 5, 6 to the detector 8. In operation, air from different zones is directed from inlet tubes through the valve to a common gas or smoke detector 8. Upon detection of gas or smoke, an alarm is energized and the valve is operated to successively direct air from each tube to the detector so as to enable location of the zone giving rise to the gas or smoke.
Conventional multi-point gas or smoke sampling systems employ individually operated valves combined on a manifold or rotary valves, such as the type described above, allowing several tubes to be scanned sequentially with one device.
Where the number of tubes to be sampled is high then the cost and/or space requirements of the individual valving systems or multiple rotary valves becomes prohibitive.
The present invention aims to at least in part alleviate problems associated with prior multi-tube aspirated gas and smoke alarm systems, as well as providing a cost effective and efficient monitoring system.
Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.